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Cited by 424Thermal properties of materialsThermography and Photoacoustic TechniquesMechanical and Thermal Properties Analysis

Tutorial: Time-domain thermoreflectance (TDTR) for thermal property characterization of bulk and thin film materials

Open access
Jiang, Puqing, Qian, Xin, Yang, Ronggui·2018·Journal of Applied Physics
DOI 10.1063/1.5046944
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Abstract

Measuring thermal properties of materials is not only of fundamental importance in understanding the transport processes of energy carriers (electrons and phonons in solids) but also of practical interest in developing novel materials with desired thermal properties for applications in energy conversion and storage, electronics, and photonic systems. Over the past two decades, ultrafast laser-based time-domain thermoreflectance (TDTR) has emerged and evolved as a reliable, powerful, and versatile technique to measure the thermal properties of a wide range of bulk and thin film materials and their interfaces. This tutorial discusses the basics as well as the recent advances of the TDTR technique and its applications in the thermal characterization of a variety of materials. The tutorial begins with the fundamentals of the TDTR technique, serving as a guideline for understanding the basic principles of this technique. Several variations of the TDTR technique that function similarly as the standard TDTR but with their own unique features are introduced, followed by introducing different advanced TDTR configurations that were developed to meet different measurement conditions. This tutorial closes with a summary that discusses the current limitations and proposes some directions for future development.

AI snapshot

Written from the paper’s full text.

TL;DR

This tutorial reviews time-domain thermoreflectance (TDTR) for measuring thermal properties of bulk and thin-film materials and interfaces, covering principles, variations, advanced configurations, and limitations. It presents TDTR as a versatile ultrafast pump-probe technique capable of measuring thermal conductivities from ~0.03 to ~2000 W m⁻¹ K⁻¹ and interface conductances from ~8 to ~3700 MW m⁻² K⁻¹.

Key findings

  • TDTR can simultaneously determine through-plane thermal conductivity and interface conductance; benchmark bulk measurements from 0.2 to 2000 W m⁻¹ K⁻¹ agree with literature values within ±8%.
  • Frequency-dependent TDTR can simultaneously determine thermal conductivity and heat capacity; bulk Si heat capacity agreed within ±5%, standard bulk samples overall within ±8%, and dual-frequency TDTR improved thin-film Kz accuracy by ~3 times, reducing a ~20% Cu-film discrepancy to agreement with four-point measurements.
  • Anisotropic configurations extend TDTR: variable spot size requires Kr > 5 W m⁻¹ K⁻¹; beam-offset measured ZnO in-plane Kr = 38.5 W m⁻¹ K⁻¹; elliptical-beam measured ZnO Ka = 46 W m⁻¹ K⁻¹ and Kc = 56 W m⁻¹ K⁻¹.
  • TDTR has been applied across broad ranges, including ultralow ~0.03 W m⁻¹ K⁻¹ for disordered WSe₂ films, high ~2000 W m⁻¹ K⁻¹ for diamond, lowest interface conductance ~8 MW m⁻² K⁻¹ for Bi/hydrogen-terminated diamond, and highest ~3700 MW m⁻² K⁻¹ for Al/Cu.

Methods

  • Tutorial/review design: explains TDTR basics, thermal transport modeling, signal processing, variations (FDTR, TR-MOKE, ASOPS), and advanced configurations for simultaneous K/C, thermally thin films, anisotropic transport, and phonon mean free path probing, with 23 figures and 244 references.
  • Data/sample: no new primary dataset; synthesizes literature and example measurements, including GaN, Si, Cu, ZnO, SiGe, superlattices, polymers, and other bulk/thin-film systems.
  • Main analysis: describes frequency-domain heat diffusion in multilayer stacks, quadrupole method, lock-in detection, sensitivity coefficients, uncertainty propagation, and benchmark comparisons.

Limitations

  • Stated: TDTR requires optically smooth surfaces, with a rule-of-thumb RMS roughness <15 nm; modulation frequency is typically 0.2–20 MHz and spot size 1–30 µm, limiting in-plane Kr <5 W m⁻¹ K⁻¹ and thermally thin films; monolayer/few-layer 2D materials cannot currently be measured; diffusion-equation analysis assumes equilibrium and may fail when mean free paths are comparable to characteristic lengths; low-temperature <30 K and high-temperature Al transducer <600 K measurements are challenging.
  • Stated: no convincing approach has yet appeared for reconstructing phonon mean free paths; rough samples require alternative bonding or TR-MOKE approaches that are not rigorously proven.
  • Evident: as a tutorial/review, conclusions rely on cited studies and example datasets rather than a single controlled new experiment, and quantitative uncertainties vary by configuration and sample.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1063/1.5046944

Cites

234 of 234 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

46 of 193 cited sources checked · 32 supported · 0 flagged · accuracy not yet measured

  • Interpretationcitation
    § Abstract:

    Over the past two decades, TDTR has emerged and evolved as a reliable, powerful, and versatile technique to measure thermal properties of a wide range of bulk and thin film materials and their interfaces.

    “Over the past two decades, ultrafast laser-based time-domain thermoreflectance (TDTR) has emerged and evolved as a reliable, powerful, and versatile technique to measure the thermal properties of a wide range of bulk and thin film materials and their interfaces.”
    • Also stated in: § I. INTRODUCTION · plain
      “Over the past two decades, ultrafast laser-based transient thermoreflectance (TTR) methods have emerged and evolved into a powerful and versatile technique 22-25 for characterizing thermal properties of a large variety of samples including both thin films 26-31 with a thickness down to ~20 nm, 26, 27 and bulk materials 32-35 .”
    Quote in the paperNot a substantial claim1 of 10 sources checked
    • cites [22] 2004, Rev. Sci. Instrum. source
    • cites [23] 2008, Rev. Sci. Instrum. source
    • cites [24] 2008, Rev. Sci. Instrum. source
    • cites [25] 2010, J. Appl. Phys. source
    • cites [26] 2007, Science source
    • cites [27] 2012, Science source
    • cites [28] 2010, Appl. Phys. Lett. source
    • cites [29] 2012, Phys. Rev. Lett. source
    • cites [30] 2016, Adv. Mater. Interfaces source
    • cites [31] 2016, Nano Lett. source

      The paper calls TDTR a standard thermal-characterization method and uses it to measure thermal conductivity in graphite films (p. 3). It also fits interface thermal conductance in a multilayer sample (p. 4). It does not establish the claimed two-decade evolution or use across a wide range of bulk and thin-film materials. (LLM, conf=0.85)

      Experimental — accuracy not yet measured
  • Premisecitation
    § A. Basic principles and implementation

    The spatial separation approach for suppressing the reflected pump beam works well for optically smooth samples with surface roughness <15 nm.

    “This approach has the merit of simple configuration and works well for optically smooth samples with surface roughness <15 nm. 12”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [12] 2014, Appl. Phys. Rev. source

      The Implementation section identifies spatial separation with an aperture as a way to suppress the reflected pump beam. The Limitations section gives <15 nm rms roughness as an approximate rule of thumb for TDTR measurements generally, not a performance threshold specifically established for spatial separation. The source also does not describe that approach as having a simple configuration. Page numbers were not provided for these passages. (LLM, conf=0.84)

      Experimental — accuracy not yet measured
  • Premisecitation
    § B. Thermal transport modeling and signal processing

    The majority of experimental work in the literature deduced thermal properties based on Fourier's law of heat conduction with an effective thermal conductivity.

    “Similarly, while TDTR can be used to study non-equilibrium phenomena such as quasi-ballistic phonon transport 90, 91, 109-111 and electronphonon coupling 55 due to its ability to detect temperature evolutions at micrometer-scale and picosecond-scale resolutions, the majority of the experimental work in the literature deduced thermal properties based on Fourier's”
    Quote in the paperNot a substantial claim4 of 6 sources checked
    • cites [90] 2007, Phys. Rev. B source
    • cites [91] 2011, Phys. Rev. Lett. source

      The paper’s main text (page not specified in our copy) says that transient thermoreflectance extracts thermal properties by fitting temperature-decay data to a thermal model, and it reports fitted thermal conductivities that differ with heater size. It does not establish that a majority of experimental work in the literature used Fourier’s law with an effective thermal conductivity. (LLM, conf=0.82)

      Experimental — accuracy not yet measured
    • cites [109] 2014, Phys. Rev. B source
    • cites [110] 2015, Phys. Rev. B source

      The Implications for transient laser thermoreflectometry section (p. 7) says many observations of quasi-ballistic heat flow are interpreted with modified Fourier theory using a reduced effective thermal conductivity. The Introduction (p. 1) calls such models conventional for experimental analysis, but the paper does not establish that a majority of experimental work in the literature uses them. (LLM, conf=0.82)

      Experimental — accuracy not yet measured
    • cites [111] 2015, Phys. Rev. B source
    • cites [55] 2015, J. Appl. Phys. source
  • Interpretationreasoning
    § C. Measurements of through-plane thermal conductivity and interface thermal conductance

    TDTR is often used to measure the through-plane thermal conductivity Kz of the sample and the transducer/sample interface conductance G without much elaboration.

    “Therefore, TDTR is often used to measure the through-plane thermal conductivity Kz of the sample and the transducer/sample interface conductance G without much elaboration.”
    Quote in the paperNot a substantial claim1 of 8 sources checked
    • cites [12] 2014, Appl. Phys. Rev. source
    • cites [40] 2005, Phys. Rev. B source
    • cites [120] 2002, J. Heat Transfer source
    • cites [121] 2005, Phys. Rev. B source
    • cites [122] 2007, Acta Mater. source
    • cites [123] 2009, J. Appl. Phys. source
    • cites [124] 2011, Adv. Mater. source
    • cites [125] 2013, Phys. Rev. B source
  • Interpretationcitation
    § B. Time-resolved magneto-optic Kerr effect (TR-MOKE)

    The small thermal mass of the transducer layer also enables enhanced sensitivity to the interface thermal conductance when the thermal conductivity of the substrate is small.

    “Meanwhile, the small thermal mass of the transducer layer also enables an enhanced sensitivity to the interface thermal conductance 150 when the thermal conductivity of the substrate is small.”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [150] 2017, Phys. Rev. B source
  • Classified as probably not a substantial claim. 37
  • May combine two claims. 61
  • The quote only partly states this claim. 1

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation
    § I. INTRODUCTION

    TDTR has been frequently used to measure the heat capacity of new materials and the thermal conductance of various solid/solid interfaces.

    “The heat capacity of new materials 38, 39 and thermal conductance of various solid/solid interfaces 40-47 have also been frequently measured using TDTR.”
    Quote in the paperNot a substantial claim2 of 10 sources checked
    • cites [38] 2013, Rev. Sci. Instrum. source
    • cites [39] 2013, Rev. Sci. Instrum. source
    • cites [40] 2005, Phys. Rev. B source
    • cites [41] 2006, Phys. Rev. B source
    • cites [42] 2014, Appl. Phys. Lett. source
    • cites [43] 2015, Nat. Commun. source
    • cites [44] 2015, Phys. Rev. B source
    • cites [45] 2016, J. Heat Transfer source
    • cites [46] 2003, Phys. Rev. B source
    • cites [47] 2012, Nat. Mater. source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § I. INTRODUCTION

    TDTR has been applied to measure materials with thermal conductivity values ranging from about 2000 W m−1 K−1 (e.g., diamond and graphite) to as low as 0.03 W m−1 K−1 (e.g., disordered WSe2 films).

    “In particular, time-domain thermoreflectance (TDTR) technique has been applied for measuring materials with thermal conductivity values ranging from a high end at ~2000 W m -1 K -1 (like diamond 36 and graphite 24, 37 ) to as low as 0.03 W m -1 K -1 (e.g., disordered WSe2 films 26 ).”
    Quote in the paperNot a substantial claim1 of 4 sources checked
    • cites [36] 2018, ACS Appl. Mater. Interfaces source
    • cites [24] 2008, Rev. Sci. Instrum. source
    • cites [37] 2017, Rev. Sci. Instrum. source

      Results and Discussions (p. 19) says TDTR has been applied to measure through-plane conductivity from about 2000 W m−1 K−1 in diamond to about 0.03 W m−1 K−1 in disordered layered crystals and fullerene derivatives. The paper also reports an in-plane measurement near 2000 W m−1 K−1 for highly ordered pyrolytic graphite (table, p. 22). Our copy does not identify the low-conductivity material as disordered WSe2 films. (LLM, conf=0.86)

      Experimental — accuracy not yet measured
    • cites [26] 2007, Science source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductcitation
    § B. Thermal transport modeling and signal processing

    Care should be taken when applying a diffusive thermal transport model to systems where a significant fraction of heat is carried by phonons with long mean-free paths (MFPs).

    “However, care should be taken when applying a diffusive thermal transport model to systems where a significant fraction of heat is carried by phonons with long mean-free paths (MFPs). 90-92, 112”
    Quote in the paperNot a substantial claim3 of 4 sources checked
    • cites [90] 2007, Phys. Rev. B source
    • cites [91] 2011, Phys. Rev. Lett. source
    • cites [92] 2013, Nat. Commun. source
    • cites [112] 2014, Nat. Commun. source

  • May combine two claims.

    Premisecitation
    § A. Frequency-domain thermoreflectance (FDTR)

    BB-FDTR was introduced to study phonon mean free path spectra in semiconductors, similar to frequency-dependent TDTR based on the physical picture of non-diffusive phonon transport.

    “For example, it was introduced to study phonon MFP spectra in semiconductors, 92, 147, 148 similar to the frequency-dependent TDTR that is based on the physical picture of non-diffusive phonon transport, see more details in Section IV(D).”
    Quote in the paperNot a substantial claim2 of 3 sources checked
    • cites [92] 2013, Nat. Commun. source
    • cites [147] 2013, Rev. Sci. Instrum. source
    • cites [148] 2013, Sci. Rep. source

  • May combine two claims.

    Interpretationcitation
    § C. Asynchronous optical sampling (ASOPS)

    ASOPS-TDTR has approximately 10 times faster data acquisition speed and is free of artefacts associated with the moving delay stage.

    “This ASOPS-TDTR technique, with its ~10 times faster data acquisition speed and free of artefacts associated with the moving delay stage, has been successfully employed in several studies”
    Quote in the paperNot a substantial claim2 of 2 sources checked
    • cites [174] 2010, Nat. Mater. source

      The main text (p. 5) says the heterodyne thermoreflectance setup eliminates the mechanical translation stage to avoid associated artefacts. Neither that passage nor the setup description (p. 11) reports an approximately tenfold increase in data-acquisition speed. (LLM, conf=0.86)

      Experimental — accuracy not yet measured
    • cites [173] 2017, Rev. Sci. Instrum. source

      The Introduction (p. 2) says asynchronous optical sampling replaces the mechanical delay line and suppresses beam-defocusing and overlap artefacts. The high-throughput setup section reports faster acquisition, but its comparison gives about 80 s versus 1 s per acquisition (p. 4), and a 45-fold reduction in total measurement time (p. 5), not an approximately tenfold gain. (LLM, conf=0.88)

      Experimental — accuracy not yet measured

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § B. Time-resolved magneto-optic Kerr effect (TR-MOKE)

    Magnetic transducers as thin as 4.2 nm have been used for TR-MOKE experiments.

    “Magnetic transducers as thin as 4.2 nm were also used for TR-MOKE experiments. 150”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [150] 2017, Phys. Rev. B source

  • May combine two claims.

    Study design and conductcitation
    § B. Measurements of thermal conductance in thermally thin films

    The dual-frequency TDTR approach was verified by measuring the through-plane thermal conductivity of a 3 μm-thick Cu film on a SiO2 substrate, with excellent agreement with four-point measurements, whereas conventional TDTR showed approximately 20% discrepancy.

    “This dual-frequency TDTR approach was verified by measuring the through-plane thermal conductivity of a 3μ m-thick Cu film on a SiO2 substrate. 184”
    • Also stated in: § B. Measurements of thermal conductance in thermally thin films · plain
      “Excellent agreement was achieved between the dual-frequency TDTR measurements and the four-point measurements of this Cu film, whereas the conventional TDTR measurements showed ~20% discrepancy from the four-point measurements. 184”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [184] 2016, Rev. Sci. Instrum. source

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Findingcitation
    § B. Time-resolved magneto-optic Kerr effect (TR-MOKE)

    Both the M+ and M- signals in Figure 13(a) show observable oscillations in the short delay time range up to 500 ps, which was attributed by the authors to Brillouin scattering.

    “Note that both the M+ and Msignals in Figure 13(a) show observable oscillations in the short delay time range up to 500 ps (see the inset of Figure 13(a)), which was attributed by the authors to the Brillouin scattering. 151”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [151] 2016, Adv. Electron. Mater. source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationcitation
    § C. Asynchronous optical sampling (ASOPS)

    A small beat frequency of Δf = 1 Hz is usually needed so that a time constant of 30 μs can be chosen for the lock-in amplifier to avoid signal aliasing.

    “A small beat frequency of Δ f =1 Hz is usually needed so that a time constant of 30 μ s can be chosen for the lock-in amplifier to avoid signal aliasing. 173”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [173] 2017, Rev. Sci. Instrum. source

      The High-throughput thermoreflectance setup section (p. 3) reports a 1 Hz oscillator frequency shift and a lock-in time constant rendered in our copy as “30 s” (the unit may have been lost in extraction). It says the time constant was set for acquisition-speed purposes, not that 1 Hz is usually needed to permit a 30 μs setting or to avoid signal aliasing. (LLM, conf=0.84)

      Experimental — accuracy not yet measured

  • May combine two claims.

    Interpretationcitation
    § D. Probing phonon mean free paths

    The simple interpretation that phonons with Λ > dp do not contribute to the apparent thermal conductivity works as a good approximation only for semiconductor alloys due to their extremely broad MFP distributions but not for pure crystals.

    “This simple interpretation, however, works as a good approximation only for semiconductor alloys due to their extremely broad MFP distributions 209 but not for pure crystals, as frequency dependence was not observed in TDTR measurements of crystalline Si despite its very long MFPs of phonons 185, 187 .”
    Quote in the paperNot a substantial claim2 of 3 sources checked
    • cites [209] 2014, Phys. Rev. B source
    • cites [185] 2016, J. Appl. Phys. source
    • cites [187] 2011, Phys. Rev. B source

      Section E, “Thermal conductivity from lattice dynamics” (page unavailable), supports the cited point that pure crystalline silicon has very long phonon mean free paths: nearly half its thermal conductivity comes from phonons with MFPs above 1 µm. The paper does not establish that the Λ > dp interpretation works only for semiconductor alloys, or report the stated TDTR frequency-dependence result. (LLM, conf=0.86)

      Experimental — accuracy not yet measured

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § D. Probing phonon mean free paths

    Recent advances in atomistic simulations have enabled the calculations of phonon properties including phonon dispersions and phonon lifetimes with good accuracy, even without input parameters.

    “Recent advances in atomistic simulations have enabled the calculations of phonon properties including phonon dispersions and phonon lifetimes with good accuracy, even without input parameters. 196-200”
    Quote in the paperNot a substantial claim3 of 5 sources checked
    • cites [196] 2007, Appl. Phys. Lett. source

      The passage indexed under Abstract (page not supplied) says density-functional perturbation theory has shown good predictive ability for phonon dispersions and lifetimes. It also describes an approach without adjustable parameters, but explicitly says that harmonic and anharmonic interatomic force constants are required as inputs. Thus, 'without input parameters' overstates what the paper says. (LLM, conf=0.83)

      Experimental — accuracy not yet measured
    • cites [197] 2014, Comput. Phys. Commun. source
    • cites [198] 2014

      Not checked in the free run.

    • cites [199] 2016, Nanoscale Microscale Thermophys. Eng. source
    • cites [200] 2017, Phys. Rev. B source

      The paper’s Abstract (page not provided) reports first-principles calculations of phonon scattering rates and optical phonon lifetimes for BAs, Si, and diamond. Our copy does not establish accurate calculation of phonon dispersions or validate the calculated lifetimes against measurements, so those parts of the broader claim are not supported. (LLM, conf=0.84)

      Experimental — accuracy not yet measured

  • May combine two claims.

    Interpretationcitation
    § C3. Elliptical-beam TDTR configuration

    The Kc of ZnO determined from the elliptical-beam method (56 W m-1 K-1) is slightly lower than a first-principles calculation in literature (62 W m-1 K-1) but is consistent with another TDTR measurement of Kz of ZnO [0001] (55 W m-1 K-1).

    “The Kc of ZnO determined from the elliptical-beam method (56 W m -1 K -1 ) is slightly lower than a first-principles calculation in literature (62 W m -1 K -1 ) 195 but is consistent with another TDTR measurement of Kz of ZnO [0001] (55 W m -1 K -1 ) 37 , which has its c -axis along the through-plane direction.”
    Quote in the paperNot a substantial claim2 of 2 sources checked
    • cites [195] 2016, Sci. Rep. source
    • cites [37] 2017, Rev. Sci. Instrum. source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § V. SUMMARY AND OUTLOOKS

    Many attempts have been made on direct TDTR measurements of semiconductors without metal transducers.

    “While many attempts have been made on direct TDTR measurements of semiconductors without metal transducers, 223-227”
    Quote in the paperNot a substantial claim2 of 5 sources checked
    • cites [223] 2016, Rev. Sci. Instrum. source
    • cites [224] 2010, J. Appl. Phys. source
    • cites [225] 2014, Nucl. Instrum. Methods Phys. Res. B source
    • cites [226] 2018, J. Phys. Condens. Matter source

      The Discussion and Conclusion describe thermoreflectance measurements on bare Bi₂Se₃, supporting the point that a semiconductor was measured without a metal layer. The Introduction identifies this paper’s method as frequency-domain lateral thermoreflectance, not TDTR, and this paper alone does not establish that many direct TDTR attempts have been made. Page numbers are unavailable in our copy. (LLM, conf=0.84)

      Experimental — accuracy not yet measured
    • cites [227] 2016, J. Appl. Phys. source

  • May combine two claims.

    Premisecitation
    § V. SUMMARY AND OUTLOOKS

    TDTR can also be applied to characterize thermal properties of liquids and fluids, such as the thermal conductivity/heat capacity of liquids, thermal conductance of solid/liquid interfaces, the heat transfer coefficient of fluids during evaporation, condensation, microchannel cooling, and flow boiling.

    “For example, TDTR can also be applied to characterize thermal properties of liquids and fluids, such as the thermal conductivity/heat capacity of liquids, 103 thermal conductance of solid/liquid interfaces, 80, 233, 234 the heat transfer coefficient of fluids during evaporation, 235, 236 condensation, 237 microchannel cooling, 238 and flow boiling. 239”
    Quote in the paperNot a substantial claim2 of 6 sources checked
    • cites [103] 2008, Rev. Sci. Instrum. source
    • cites [80] 2006, Phys. Rev. Lett. source
    • cites [233] 2015, Appl. Phys. Lett. source
    • cites [234] 2013, Appl. Phys. Lett. source
    • cites [235] 2012, Int. J. Heat Mass Transfer source
    • cites [236] 2014, J. Heat Transfer source

  • May combine two claims.

    Findingnone given
    § C. Measurements of through-plane thermal conductivity and interface thermal conductance

    The major sources of measurement uncertainty come from the thermal capacitance of the transducer for high-frequency measurements and from the laser spot size w0 for low-frequency measurements.

    “The major sources of measurement uncertainty come from the thermal capacitance (volumetric heat capacity times the film thickness, C*h ) of the transducer for high-frequency measurements and from the laser spot size w 0 for low-frequency measurements.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingcitation
    § C. Measurements of through-plane thermal conductivity and interface thermal conductance

    The highest thermal conductance observed to date is for metal/metal interfaces, such as Al/Cu, with a G of about 3700 MW m-2 K-1 at room temperature.

    “while the highest thermal conductance observed to-date is for metal/metal interfaces, such as Al/Cu, with a G of ~3700 MW m -2 K -1 at room temperature. 40”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [40] 2005, Phys. Rev. B source

  • May combine two claims.

    Findingown data
    § A. Frequency-domain thermoreflectance (FDTR)

    Both CW and pulsed FDTR have similar sensitivities to the thermal conductivity and heat capacity of the substrate; however, the signals of pulsed FDTR are much more sensitive to the spot size w0 and the heat capacitance of the transducer film.

    “The results show that both the CW and pulsed FDTR have similar sensitivities to the thermal conductivity and heat capacity of the substrate; however, the signals of pulsed FDTR are much more sensitive to the spot size w 0 and the heat capacitance ( C Al h Al) of the transducer film.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data
    § C. Measurements of through-plane thermal conductivity and interface thermal conductance

    The sensitivity to Kz remains positive over the whole delay time range, indicating that Kz mainly affects the amplitude of the ratio signal.

    “On the other hand, the sensitivity to Kz remains positive over the whole delay time range, indicating that Kz mainly affects the amplitude of the ratio signal.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingcitation
    § C. Measurements of through-plane thermal conductivity and interface thermal conductance

    The through-plane thermal conductivities of the benchmark materials determined by TDTR are in good agreement with literature values with an overall experimental uncertainty of plus or minus 8%.

    “The throughplane thermal conductivities of these materials determined by TDTR are in good agreement with the literature values with an overall experimental uncertainty of ±8%.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data
    § C. Measurements of through-plane thermal conductivity and interface thermal conductance

    Kz and G can be determined with an uncertainty of about 10% and about 5%, respectively, at both frequencies of 1 and 10 MHz.

    “The results show that Kz and G can be determined with an uncertainty of ~10% and ~5%, respectively, at both frequencies of 1 and 10 MHz.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data
    § C. Measurements of through-plane thermal conductivity and interface thermal conductance

    The modulation frequency has very little effect on the sensitivity to Kz but affects the sensitivity to G dramatically.

    “Comparison of the sensitivity coefficients at 1 and 10 MHz suggests that the modulation frequency has a very little effect on the sensitivity to Kz but affects the sensitivity to G dramatically.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data
    § C. Measurements of through-plane thermal conductivity and interface thermal conductance

    Kz of the sample mainly affects the amplitude of the ratio signal, whereas the interface conductance G mainly affects the gradient of the ratio signal.

    “As indicated by the ±30% bounds of the best-fitted value in Figure 4(c, d), Kz of the sample mainly affects the amplitude of the ratio signal, whereas the interface conductance G mainly affects the gradient of the ratio signal.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingcitation
    § C. Measurements of through-plane thermal conductivity and interface thermal conductance

    Ultra-low thermal conductivities of full-dense solid materials were reported for fullerene derivatives at room temperature (~0.05 W m-1 K-1) and disordered layered WSe2 thin films at cryogenic temperatures (~0.03 W m-1 K-1), both measured using TDTR.

    “Ultra-low thermal conductivities of full-dense solid materials were reported for fullerene derivatives at room temperature (~0.05 W m -1 K -1 ) 125 and disordered layered WSe2 thin films at cryogenic temperatures (~0.03 W m -1 K -1 ) 26 , both measured using TDTR.”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [125] 2013, Phys. Rev. B source
    • cites [26] 2007, Science source

  • May combine two claims.

    Findingown data
    § C. Measurements of through-plane thermal conductivity and interface thermal conductance

    At 10 MHz, the sensitivity to G changes from positive to negative over the delay time range of 0.1-10 ns, indicating that G mainly affects the gradient of the ratio signal.

    “At 10 MHz, the sensitivity to G changes from positive to negative over the delay time range of 0.1-10 ns, indicating that G mainly affects the gradient of the ratio signal.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data
    § A. Frequency-domain thermoreflectance (FDTR)

    The phase signal of pulsed FDTR changes relatively little over the modulation frequency range of 0.05-20 MHz, while the phase signal of CW FDTR changes dramatically as a function of frequency.

    “The phase signal ߮ of the pulsed FDTR changes relatively little over the modulation frequency range of 0.05-20 MHz, while the phase signal ߮ of the CW FDTR changes dramatically as a function of frequency.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data
    § A. Frequency-domain thermoreflectance (FDTR)

    Both CW and pulsed FDTR configurations have almost identical V_out signals but the V_in signals differ significantly, suggesting that the V_out signals in TDTR experiments mainly come from the continuous heating at the modulation frequency.

    “The results show that both CW and pulsed FDTR configurations have almost the identical V out signals but the V in signals differ significantly, suggesting that the V out signals in TDTR experiments mainly come from the continuous heating at the modulation frequency.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingcitation
    § D. Probing phonon mean free paths

    Minnich et al. found that the apparent thermal conductivity of crystalline Si deviated from the bulk thermal conductivity values and decreased with a smaller laser spot size.

    “They found that the apparent thermal conductivity of crystalline Si, which was determined from the best fit of TDTR experimental data by a thermal model prediction based on the heat diffusion equation, deviated from the bulk thermal conductivity values and decreased with a smaller laser spot size, as shown in Figure 22(a). 91”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Minnich et al. 91

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Findingcitation
    § D. Probing phonon mean free paths

    The laser spot size-dependent thermal conductivity of Si was converted to the 'MFP spectrum' of Si, which qualitatively agrees with the first-principles predictions of thermal conductivity accumulation function.

    “Using Eq.(4.13), the laser spot size-dependent thermal conductivity were thus converted to the 'MFP spectrum' of Si, as shown by the symbols in Figure 22(b), which qualitatively agrees with the first-principles predictions of thermal conductivity accumulation function (shown as the curves in Figure 22(b)). 91”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Minnich et al. 91

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Findingown data
    § C3. Elliptical-beam TDTR configuration

    The beam-offset and elliptical-beam methods compare relatively well with each other, with the measured in-plane thermal conductivities within the error bars.

    “Overall, these two methods compare relatively well with each other, with the measured in-plane thermal conductivities within the error bars.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingcitation
    § D. Probing phonon mean free paths

    The MFP spectrum α(Λ) of SiGe was reconstructed from the measured apparent thermal conductivity values and is in good agreement with the first-principles prediction of thermal conductivity accumulation function.

    “The MFP spectrum ߙ ሺΛሻ of SiGe was reconstructed based on Eq.(4.14) from the measured apparent thermal conductivity values, shown as the symbols in Figure 23(d), which are in good agreement with the first-principles prediction of thermal conductivity accumulation function (the dashed line in Figure 23(d)).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Hu et al. 206

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Findingcitation
    § D. Probing phonon mean free paths

    Regner et al. measured the accumulation function of silicon using BB-FDTR, but their results failed to compare well with first-principles predictions at cryogenic temperatures.

    “Assuming the same cutoff length of ܮ ୡ ൌ ݀ ௣ , Regner et al . 92 measured the accumulation function of silicon using a variation of TDTR, the broadband frequency-domain thermoreflectance (BB-FDTR), as described in Section III(A). However, their results failed to compare well with first-principles predictions at cryogenic temperatures.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Regner et al. 92

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Findingnone given
    § C3. Elliptical-beam TDTR configuration

    The data by the beam-offset method scatter more significantly whereas the data by the elliptical-beam method show better consistency.

    “However, the data by the beam-offset method scatter more significantly whereas the data by the elliptical-beam method show better consistency.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation
    § A. Basic principles and implementation

    For a Ti:sapphire oscillator centered around 800 nm, an Al thin layer with thickness about 100 nm is a common choice as the transducer layer due to its strong absorption (99% absorption depth <60 nm) and exceptionally large thermoreflectance coefficient dR/dT ~10−4 K−1 at 800 nm.

    “For a Ti:sapphire oscillator centered around 800 nm, an Al thin layer with a thickness of ~100 nm is a common choice as the transducer layer due to its strong absorption (the 99% absorption depth is <60 nm) 104 and an exceptionally large thermoreflectance coefficient d R /d T ~ 10 -4 K -1 at the 800-nm wavelength. 98, 105, 106”
    Quote in the paperNot a substantial claim0 of 4 sources checked
    • cites [104] 1991

      Not checked in the free run.

    • cites [98] 2012, Opt. Express source
    • cites [105] 2010, J. Appl. Phys. source
    • cites [106] 2015, Rev. Sci. Instrum. source

  • May combine two claims.

    Premisecitation
    § B. Thermal transport modeling and signal processing

    The key advance in the data analysis of TDTR experiments was made by Cahill in 2004, solving the three-dimensional heat diffusion equation through multi-layered structures with consideration of the pulse accumulation effect.

    “The key advance in the data analysis of TDTR experiments was made by Cahill in 2004. 22 The three-dimensional heat diffusion equation through multi-layered structures was solved with the consideration of the so-called 'pulse accumulation' effect”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [22] 2004, Rev. Sci. Instrum. source

  • Classified as probably not a substantial claim. May combine two claims.

    Premisenone given
    § A. Basic principles and implementation

    The TDTR method measures the thermoreflectance response as a function of delay time between the arrival of the pump and probe pulses on the sample surface, where the pump beam deposits a periodic heat flux on the sample surface and the probe beam detects the corresponding temperature change through the reflectance change.

    “The TDTR method measures the thermoreflectance response as a function of delay time between the arrival of the pump and probe pulses on the sample surface, where the pump beam deposits a periodic heat flux on the sample surface and the probe beam detects the corresponding temperature change through the reflectance change.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation
    § A. Basic principles and implementation

    The two-tint method has a high demand on laser stability in both intensity and wavelength; otherwise fluctuations in laser wavelength translate into fluctuations in the power intensities of the pump and probe beams and appear as noise in TDTR measurements.

    “In addition, the two-tint method has a high demand on the laser stability in both the intensity and the wavelength (like the one reported in Ref. 23 ). Otherwise, the fluctuations in the laser wavelength would translate into fluctuations in the power intensities of the pump and probe beams and appear as noise in TDTR measurements (like the one reported in Ref. 95 ).”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [23] 2008, Rev. Sci. Instrum. source
    • cites [95] 2016, Rev. Sci. Instrum. source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § A. Basic principles and implementation

    The transient thermoreflectance technique can be implemented as both the TDTR method and the frequency-domain thermoreflectance (FDTR) method.

    “The transient thermoreflectance technique can be implemented as both the TDTR method 22, 24, 25 and the frequency-domain thermoreflectance (FDTR) method 93, 94 (see Section III(A) for more details of FDTR).”
    Quote in the paperNot a substantial claim0 of 5 sources checked
    • cites [22] 2004, Rev. Sci. Instrum. source
    • cites [24] 2008, Rev. Sci. Instrum. source
    • cites [25] 2010, J. Appl. Phys. source
    • cites [93] 2009, Rev. Sci. Instrum. source
    • cites [94] 2011, J. Heat Transfer source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisenone given
    § B. Thermal transport modeling and signal processing

    The determination of thermal transport properties by TDTR is typically accomplished by adjusting free parameters (the unknown thermal properties) in a thermal transport model to obtain the best fit between the model prediction and the experimental data.

    “The determination of thermal transport properties by TDTR is typically accomplished by adjusting free parameters (the unknown thermal properties) in a thermal transport model to obtain the best fit between the model prediction and the experimental data.”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim.

    Premisenone given
    § A. Basic principles and implementation

    TDTR measures thermal properties through the reflectance change with temperature, known as thermoreflectance.

    “TDTR measures thermal properties through the reflectance change with temperature, known as the thermoreflectance.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given
    § A. Basic principles and implementation

    In TDTR experiments, besides the unknown thermal properties, many other input parameters (such as laser spot size, thermal conductivity of the transducer layer, thickness and heat capacity of each layer in the sample stack) affect the signals and need to be pre-determined as accurately as possible.

    “In TDTR experiments, besides the unknown thermal properties of the sample layer to be derived, there are also many other input parameters (such as the laser spot size, thermal conductivity of the transducer layer, thickness and heat capacity of each layer in the sample stack) that affect the signals and need to be pre-determined as accurately as possible.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisenone given
    § B2. Modeling of signals acquired in TDTR experiments

    In most TDTR implementations, the pump beam is modulated by a square wave but with higher harmonics removed by a bandpass filter, while in some other configurations the pump beam is modulated by a sine wave; thus only the fundamental frequency of the modulation is of interest.

    “In most TDTR implementations, the pump beam is modulated by a square wave but with the higher harmonics of the square wave being removed by a bandpass filter, while in some other TDTR configurations, the pump beam is modulated by a sine wave. Thus, only the fundamental frequency of the modulation is of interest, as illustrated in Figure 3(a).”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Study design and conductreasoning
    § A. Basic principles and implementation

    Additional phase shift introduced by cables, electronic instruments, and optical components into measured signals needs to be corrected; it can usually be canceled based on the fact that the Vout signal in TDTR experiments should be constant across zero delay time.

    “However, cautions need to be taken to correct the additional phase shift introduced by cables, electronic instruments, and optical components into the measured signals. Usually, this phase shift due to the instrumentation can be conveniently canceled based on the fact that the V out signal in TDTR experiments should be constant across the zero delay time.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Study design and conductreasoning
    § A. Basic principles and implementation

    An estimation of the steady-state temperature rise is important for TDTR experiments, as the temperature rise needs to be small (usually <10 K) to ensure the reflectance change is linearly proportional to the temperature change.

    “An estimation of the steady-state temperature rise is also important for TDTR experiments, as the temperature rise needs to be small (usually <10 K) to ensure the reflectance change is linearly proportional to the temperature change.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisenone given
    § C. Measurements of through-plane thermal conductivity and interface thermal conductance

    Most practitioners use a large laser spot size (w0 = 5-20 micrometers) and a high modulation frequency (f = 1-10 MHz), resulting in quasi-one-dimensional thermal transport.

    “Furthermore, most practitioners use a large laser spot size ( w 0=5-20 μ m) and a high modulation frequency ( f =1-10 MHz), resulting in quasi-one-dimensional thermal transport.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation
    § I. INTRODUCTION

    TDTR requires minimal sample preparation and no delicate design of electrical heaters or temperature sensors.

    “For example, it requires minimal sample preparation and no delicate design of electrical heaters or temperature sensors, and it works equally well in regular ambient conditions or through the window of a vacuum chamber. 48”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [48] 2014, Annu. Rev. Heat Transfer source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisenone given
    § A. Basic principles and implementation

    The thermal conductivity of the metal transducer layer can be characterized using four-point probe measurement of electrical resistance and the Wiedemann-Franz law.

    “The thermal conductivity of the metal transducer layer can be characterized using four-point probe measurement of the electrical resistance and the Wiedemann-Franz law”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisenone given
    § A. Basic principles and implementation

    The formulas for steady-state temperature rise for semi-infinite solid, thin layers, and interfaces are only for a rather crude estimation.

    “Note that these formulas are only for a rather crude estimation.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisereasoning
    § A. Basic principles and implementation

    The thin metallic transducer layer makes it possible to assume a surface heat flux boundary condition and improves the overall SNR due to its large thermoreflectance coefficient.

    “The thin metallic transducer layer not only makes it possible to assume a surface heat flux boundary condition and thus simplifying the analysis but also improves the overall SNR due to its large thermoreflectance coefficient.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisereasoning
    § A. Basic principles and implementation

    An accurate and easy-to-use approach for TDTR to characterize laser spot size is to measure the spatial correlation between the pump and probe focal spots; this works well because TDTR signals are affected by the RMS average of the pump and probe spot sizes rather than their individual sizes.

    “For the characterization of the laser spot size, while many techniques such as the knife-edge method 25, 107 and patterned sample image method 94 can be used, an accurate and easy-to-use approach for TDTR is to measure the spatial correlation between the pump and probe focal spots. 39”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [39] 2013, Rev. Sci. Instrum. source

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Interpretationnone given
    § A. Frequency-domain thermoreflectance (FDTR)

    Measurements at such a high modulation frequency can be challenging due to the small thermal penetration depth and severe heating effect.

    “However, measurements at such a high modulation frequency can be challenging due to the small thermal penetration depth and severe heating effect.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premiseown data
    § C. Measurements of through-plane thermal conductivity and interface thermal conductance

    Over the past two decades, TDTR has been applied to characterize the thermal properties of a wide range of bulk and thin film materials and their interfaces.

    “Over the past two decades, TDTR has been applied to characterize the thermal properties of a wide range of bulk and thin film materials and their interfaces.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning
    § A. Frequency-domain thermoreflectance (FDTR)

    FDTR is much easier to implement because it avoids the complexity of a long mechanical delay for the time delay and it can use inexpensive CW laser sources.

    “FDTR is thus much easier to implement because it avoids the complexity of a long mechanical delay for the time delay and it can use inexpensive CW laser sources.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning
    § A. Frequency-domain thermoreflectance (FDTR)

    Regardless of how high the modulation frequency of the pump beam f1 is, the lock-in amplifier only measures signals at a much lower frequency f1-f2, which can be chosen to achieve very high SNR and retain great fidelity of the thermal signal.

    “Regardless of how high the modulation frequency of the pump beam f 1 is, the lock-in amplifier only measures the signals at a much lower frequency, f 1 -f 2, which can be chosen to be in a proper range to achieve very high SNR and retain great fidelity of the thermal signal.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning
    § C. Measurements of through-plane thermal conductivity and interface thermal conductance

    TDTR cannot measure arbitrarily thin films but usually requires the films to be thermally thick, meaning the film thickness should be larger than the through-plane thermal penetration depth.

    “Note that TDTR cannot measure any arbitrarily thin films but usually requires the films to be 'thermally thick', i.e. , the film thickness should be larger than the through-plane thermal penetration depth”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation
    § C. Measurements of through-plane thermal conductivity and interface thermal conductance

    The multivariate error-propagation formula has been validated by the Monte Carlo method but is much more computationally efficient, taking seconds rather than days.

    “This multivariate errorpropagation formula has been validated by the Monte Carlo method 127 but is much more computationally efficient: it takes only a few seconds to complete the analysis on a desktop computer using MATLAB scripts rather than a few days as needed by the Monte Carlo method.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [127] 2016, Rev. Sci. Instrum. source

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

    Interpretationnone given
    § A. Frequency-domain thermoreflectance (FDTR)

    The use of the resonant filter is not always necessary for TDTR if the pump beam is modulated by a pure sine wave, or if a digital lock-in amplifier using clean sine-wave multipliers is used, or if higher harmonics are considered in the thermal modeling.

    “The use of the resonant filter, however, is not always necessary for TDTR, if the pump beam is modulated by a pure sine wave or if a digital lock-in amplifier using clean sine-wave multipliers is used for the lock-in detection, or if the higher harmonics are also considered in the thermal modeling.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisenone given
    § B. Time-resolved magneto-optic Kerr effect (TR-MOKE)

    In case of non-perfect balancing with the half-wave plate, thermoreflectance signals overlap the transient Kerr rotation.

    “In case of non-perfect balancing with the half-wave plate, thermoreflectance signals overlap the transient Kerr rotation.”
    Quote in the paperNot a substantial claim

  • The quote only partly states this claim.

    Study design and conductcitation
    § A. Simultaneous measurements of thermal conductivity and heat capacity

    Frequency-dependent TDTR determined the heat capacity of bulk Si with ±5% agreement with the literature value.

    “A good agreement of ±5% in the determined C of bulk Si was achieved with the literature value.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [38] 2013, Rev. Sci. Instrum. source

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

    Interpretationnone given
    § C. Asynchronous optical sampling (ASOPS)

    ASOPS eliminates the mechanical delay stage and the associated systematic errors due to beam pointing instability and spot size variation.

    “ASOPS eliminates the mechanical delay stage and the associated systematic errors due to beam pointing instability and spot size variation.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisereasoning
    § C.1. Variable spot size TDTR configuration

    In variable spot size TDTR, when the laser spot size w0 is much larger than the in-plane thermal penetration depth dp,r, the TDTR signals are sensitive to through-plane thermal conductivity Kz only; when w0 is similar or smaller than dp,r, the signals are sensitive to both in-plane and through-plane thermal properties Kr and Kz.

    “When TDTR experiments are conducted using a laser spot size w 0 much larger than the in-plane thermal penetration depth dp , r , the heat mainly flows in the through-plane direction. In this case, the TDTR signals are sensitive to the through-plane thermal conductivity Kz only. When TDTR experiments are conducted using w 0 similar or even smaller than dp,r , the heat flux becomes three-dimensional”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning
    § A. Simultaneous measurements of thermal conductivity and heat capacity

    Because TDTR signals depend on K and C differently at high and low modulation frequencies, K and C can be determined simultaneously by conducting at least two sets of measurements at a high and a low modulation frequency.

    “Since the TDTR signals depend on K and C differently at high and low modulation frequencies, a K-C diagram shown in Figure 15(b) suggests that the K-C curves at the different modulation frequencies should cross at a certain point. These two properties can thus be determined simultaneously by conducting at least two sets of the measurements at a high and a low modulation frequency.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premiseown data
    § A. Simultaneous measurements of thermal conductivity and heat capacity

    At a low modulation frequency of 0.1 MHz, the sensitivities to K and C have similar amplitudes but opposite signs, so the TDTR signal is mainly affected by the thermal diffusivity of the substrate.

    “As the modulation frequency decreases to sufficiently low of 0.1 MHz, the sensitivities to K and C have the similar amplitudes but opposite signs, suggesting that the TDTR signal is mainly affected by the thermal diffusivity ߙ ൌ ܥ ܭ / of the substrate at low modulation frequencies.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [38] 2013, Rev. Sci. Instrum. source

  • May combine two claims.

    Interpretationreasoning
    § C. Asynchronous optical sampling (ASOPS)

    ASOPS probing rate can be many times slower than the pumping rate, enabling sampling of ultrafast phenomena at a much slower acquisition rate.

    “Another important feature of ASOPS is that the probing rate can be many times slower than the pumping rate, with fpump = nfprobe + Δ f , where n is an integer. This enables sampling of ultrafast phenomena at a much slower acquisition rate.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationnone given
    § C. Asynchronous optical sampling (ASOPS)

    The temporal resolution eventually achieved by ASOPS depends not only on the delay time increment but also on the pulse duration and the detection bandwidth.

    “Note that the temporal resolution eventually achieved by ASOPS depends not only on the delay time increment but also on the pulse duration and the detection bandwidth.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Interpretationreasoning
    § C. Asynchronous optical sampling (ASOPS)

    ASOPS has access to the full delay range, whereas traditional pump-probe metrology delay time is limited by the delay stage length.

    “ASOPS has access to the full delay range, whereas in the traditional pump-probe metrology the delay time is limited by the length of the delay stage.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation
    § C2. Beam-offset TDTR configuration

    In the limit dp,r >> w0, the Vout signal as a function of offset distance is proportionally dependent on Kr, making the FWHM of Vout not sensitive to changes in Kr.

    “The reason, as argued by Jiang et al . 119 , is that although the V out signal is highly dependent on Kr of the substrate in the limit dp,r &gt;&gt; w 0 , the V out signal as a function of the offset distance is proportionally dependent on Kr , making the FWHM of V out not sensitive to the change in Kr .”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Jiang et al. 119

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Premisecitation
    § C2. Beam-offset TDTR configuration

    With dp,r ≈ w0, only the Vout signals in the short offset range xc ≤ w0 are sensitive to Kr, making the FWHM of Vout highly sensitive to changes in Kr.

    “On the other hand, with dp,r ≈ w 0, only the V out signals in the short offset range xc ≤ w 0 are sensitive to Kr , making the FWHM of V out highly sensitivity to the change in Kr .”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Jiang et al. 119

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationreasoning
    § B. Time-resolved magneto-optic Kerr effect (TR-MOKE)

    Adsorbents such as hydrocarbons and water molecules on the sample surface can possibly change the effective heat capacity of the transducer and need to be carefully considered in the thermal model.

    “Given the small thermal masses of the magnetic transducers, adsorbents such as hydrocarbons and water molecules on the sample surface can possibly change the effective heat capacity of the transducer and need to be carefully considered in the thermal model.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation
    § A. Simultaneous measurements of thermal conductivity and heat capacity

    The heat capacities of the hybrid zincone films were independent of film thickness, while their thermal conductivities changed slightly with film thickness.

    “The heat capacities of the hybrid films were found to be independent of the film thickness, while the thermal conductivities changes slightly with the film thickness.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [181] 2013, Nano Lett. source

  • May combine two claims.

    Premisecitation
    § C2. Beam-offset TDTR configuration

    For samples with Kr > 30 W m-1 K-1, both NbV and Al transducers work well, giving an uncertainty of <15% for the Kr measurements.

    “For samples with Kr &gt; 30 W m -1 K -1 , both NbV and Al transducers work well, giving an uncertainty of &lt;15% for the Kr measurements.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Jiang et al. 119

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Interpretationcitation
    § C2. Beam-offset TDTR configuration

    With a much-reduced thermal conductance of the metal film, the FWHM signal in beam-offset TDTR is more sensitive to the thermal conductivity of the substrate and less sensitive to the properties of the transducer layer, yielding a smaller measurement uncertainty.

    “With a much-reduced thermal conductance of the metal film ( K m h m), the FWHM signal is more sensitive to the thermal conductivity of the substrate and less sensitive to the properties of the transducer layer, thus yielding a smaller measurement uncertainty. 87”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [87] 2014, Rev. Sci. Instrum. source

  • May combine two claims.

    Interpretationreasoning
    § C. Asynchronous optical sampling (ASOPS)

    Given fpump = 80 MHz and frequency offset Δf = 1 kHz, ASOPS would achieve a delay time increment of Δt = 0.16 ps, and the measurement time to finish one full period scan is only 1 ms, meaning the ASOPS instrument can obtain 1000 acquisitions within 1 second.

    “For example, given fpump = 80 MHz and frequency offset Δ f = 1 kHz, ASOPS would achieve a delay time increment of Δ t = 0.16 ps, and the measurement time to finish one full period scan is only 1 ms, which means that the ASOPS instrument can obtain 1000 acquisitions within 1 second.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premiseown data
    § A. Simultaneous measurements of thermal conductivity and heat capacity

    At a high modulation frequency of 10 MHz, the TDTR signal has the same sensitivity to K and C, so the signal is mostly determined by the thermal effusivity of the substrate.

    “At a high modulation frequency of 10 MHz, the TDTR signal has the same sensitivity to K and C , suggesting that the TDTR signal V in / V out is mostly determined by the thermal effusivity ݁ ൌ √ ܥܭ of the substrate at high modulation frequencies.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [38] 2013, Rev. Sci. Instrum. source

  • May combine two claims.

    Interpretationreasoning
    § B. Measurements of thermal conductance in thermally thin films

    In dual-frequency TDTR, conducting two sets of measurements at two different modulation frequencies and taking the ratio of the two measurements maintains sensitivity to Kz,Si while greatly reducing sensitivity to hAlCAl, thereby improving accuracy in determining Kz of the thin film.

    “one can thus conduct two sets of measurements at the two different modulation frequencies and take the ratio of the two measurements as the signal instead. In this case, the sensitivity to Kz ,Si is maintained whereas the sensitivity to h Al C Al is greatly reduced. The accuracy in determining Kz of the thin film can thus be greatly improved.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning
    § B. Time-resolved magneto-optic Kerr effect (TR-MOKE)

    Since TR-MOKE signals change signs for oppositely aligned magnetization states of the magnetic transducers, the TR-MOKE signals can be isolated by subtracting the in-phase and out-of-phase signals recorded for oppositely aligned magnetization states.

    “Since the TR-MOKE signals would change signs for oppositely aligned magnetization states of the magnetic transducers, the TR-MOKE signals can be isolated out by subtracting the in-phase and out-of-phase signals recorded for oppositely aligned magnetization states of the transducers as ܸ ௜௡ ൌ ሺ ܸ ௜௡ ெା െ ܸ ௜௡ ெି ሻ /2 and ܸ ௢௨௧ ൌ ሺ ܸ ௢௨௧ ெା െ ܸ ௢௨௧ ெି ሻ /2 .”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation
    § D. Probing phonon mean free paths

    Koh and Cahill were the first to observe a modulation-frequency-dependent thermal conductivity in some semiconductor alloys measured using TDTR, and they attributed it to the non-diffusive phonon transport.

    “Koh and Cahill 90 were the first to observe a modulation-frequency-dependent thermal conductivity in some semiconductor alloys measured using TDTR, and they attributed it to the non-diffusive phonon transport, i.e. , phonons with Λ ൐ ݀ ௣ (and Λ ൐ 2 ݀ ௣ in their later publication 209 ) do not contribute to the apparent thermal conductivity measured by TDTR.”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites Koh and Cahill 90

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [209] 2014, Phys. Rev. B source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationcitation
    § D. Probing phonon mean free paths

    Wilson and Cahill pointed out that the connection between the spot size-dependent thermal conductivity and the 'MFP spectrum' should not be that simple, as the interface between the metal transducer and the substrate also played an important role in TDTR experiments.

    “Wilson and Cahill 112 also pointed out that the connection between the spot sizedependent thermal conductivity and the 'MFP spectrum' should not be that simple, as the interface between the metal transducer and the substrate also played an important role in TDTR experiments.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Wilson and Cahill 112

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Interpretationnone given
    § D. Probing phonon mean free paths

    For purely ballistic transport with a large Λ/Lc the suppression function approaches zero, whereas for fully diffusive phonon transport with a small Λ/Lc the suppression function approaches unity.

    “For purely ballistic transport with a large ஃ ௅೎ the suppression function approaches zero, whereas for fully diffusive phonon transport with a small ஃ ௅೎ the suppression function approaches unity.”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim.

    Interpretationnone given
    § D. Probing phonon mean free paths

    Direct measurements of phonon properties remain very challenging.

    “However, their direct measurements remain very challenging.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationcitation
    § D. Probing phonon mean free paths

    Wilson and Cahill pointed out that a significant amount of the laser energy was deposited in the Cr layer instead of the surface of the Au layer due to the weak electron-phonon coupling in Au, neglect of which would cause a considerable error.

    “However, Wilson and Cahill 112 pointed out that a significant amount of the laser energy was deposited in the Cr layer instead of the surface of the Au layer due to the weak electron-phonon coupling in Au, neglect of which would cause a considerable error.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Wilson and Cahill 112

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Classified as probably not a substantial claim.

    Premisenone given
    § D. Probing phonon mean free paths

    The measured apparent thermal properties would deviate from the predictions of Fourier's law when the characteristic length is comparable to or even smaller than the phonon MFPs.

    “Based on the simple idea that the measured apparent thermal properties (thermal conductivity and interface thermal conductance) would deviate from the predictions of Fourier's law when the characteristic length is comparable to or even smaller than the phonon MFPs, some experimental work based on TDTR and its variations has been proposed to directly probe the phonon MFPs.”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim.

    Interpretationcitation
    § D. Probing phonon mean free paths

    Wilson and Cahill pointed out that the discrepancy could be due to an artifact created by the transducer thermalization.

    “Wilson and Cahill 112 later pointed out that the discrepancy could be due to an artifact created by the transducer thermalization.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Wilson and Cahill 112

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationcitation
    § D. Probing phonon mean free paths

    Wilson and Cahill pointed out that the RMS average of the pump and probe spot sizes rather than the pump spot size alone should be the characteristic length scale due to the exchange symmetry between the heater and the thermometer.

    “For example, Wilson and Cahill 112 pointed out that the RMS average of the pump and probe spot sizes rather than the pump spot size alone should be the characteristic length scale due to the exchange symmetry between the heater and the thermometer, as shown in Eq. (2.18).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Wilson and Cahill 112

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim: may not pass S2 (checkable), S3 (load-bearing), S4 (based).

    Interpretationnone given
    § D. Probing phonon mean free paths

    The assumption of a single cutoff length scale is too abrupt.

    “Besides, the assumption of a single cutoff length scale is too abrupt.”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim.

    Premisenone given
    § D. Probing phonon mean free paths

    The knowledge of phonon mean free paths (MFPs) is important in developing microscopic pictures of the heat conduction processes, especially in micro/nano-structures and in ultrafast processes where Fourier's law of heat conduction fails.

    “The knowledge of phonon mean free paths (MFPs) is important in developing microscopic pictures of the heat conduction processes, especially in micro/nano-structures and in ultrafast processes where Fourier's law of heat conduction fails.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation
    § V. SUMMARY AND OUTLOOKS

    Researchers are looking for alternative metal transducers for TDTR measurements at higher temperatures (with Pt and HfN as potential candidates) or attempting to perform TDTR measurements without metal transducers at high temperatures.

    “Researchers are looking for alternative metal transducers for TDTR measurements at higher temperatures (with Pt and HfN 229 as two examples of the potential candidates) or attempting to perform TDTR measurements without metal transducers at high temperatures. 142”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [229] 2017, Appl. Phys. Lett. source
    • cites [142] 2017, Phys. Rev. Mater. source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationreasoning
    § V. SUMMARY AND OUTLOOKS

    The advent of ultrafast laser sources with tunable wavelength over a wide range (such as a system based on an optical parametric oscillator) would be a great advantage for TDTR, as the probe wavelength could then be chosen to match a peak in the thermoreflectance of the metal transducer, thus increasing the signal-to-noise ratio significantly.

    “Meanwhile, the advent of ultrafast laser sources with tunable wavelength over a wide range (such as a system based on optical parametric oscillator 230, 231 ) would also be a great advantage for TDTR, as the probe wavelength could then be chosen to match a peak in the thermoreflectance of the metal transducer, thus increasing the signal-to-noise ratio significantly.”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [230] 2015, J. Appl. Phys. source
    • cites [231] 2010, Nat. Photon. source

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation
    § V. SUMMARY AND OUTLOOKS

    TDTR can also be easily adapted to transient absorption and be exploited to study thermophysical phenomena in nanoparticle solutions, such as the heat diffusion from particles to the surroundings and thermal transport across surfactants.

    “TDTR can also be easily adapted to transient absorption and be exploited to study thermophysical phenomena in nanoparticle solutions, such as the heat diffusion from particles to the surroundings and thermal transport across surfactants, 240-243”
    Quote in the paperNot a substantial claim0 of 4 sources checked
    • cites [240] 2008, J. Phys. Chem. C source
    • cites [241] 2005, Nano Lett. source
    • cites [242] 2013, ACS Nano source
    • cites [243] 2012, J. Phys. Chem. C source

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Interpretationreasoning
    § V. SUMMARY AND OUTLOOKS

    The application of TDTR to nanoparticle solutions can have important applications such as medical therapies using intensely heated nanoparticles.

    “which can have important applications such as medical therapies using intensely heated nanoparticles.”
    Quote in the paperNot a substantial claim
89 of 89

  • The authors state this as an assumption.

    The additional electrical resistivity of the metal film as compared to its pure bulk counterpart is dominantly caused by impurity scattering, which is temperature-independent.

    “the additional electrical resistivity of the metal film as compared to its pure bulk counterpart is assumed to be dominantly caused by impurity scattering, which is temperature-independent.”

  • The authors state this as an assumption.

    The heat capacities of the metal transducer film and the sub-layers are the same as their bulk counterparts.

    “The heat capacities of the metal transducer film and the sub-layers are usually assumed to be the same as their bulk counterparts 5 and can be obtained from the literature.”

  • The authors state this as an assumption.

    Both the laser profile and the thermal properties of the sample are axisymmetric rather than in-plane anisotropic.

    “In this basic model, both the laser profile and the thermal properties of the sample are assumed to be axisymmetric rather than in-plane anisotropic (see Section IV(C));”

  • The authors state this as an assumption.

    The different phonon modes are in thermal equilibrium so that effective thermal properties Kr, Kz, C, and G can be assumed for each layer.

    “and the different phonon modes are assumed to be in thermal equilibrium so that effective thermal properties Kr , Kz , C, and G can be assumed for each layer.”

  • The authors state this as an assumption.

    The governing equation for anisotropic heat diffusion in cylindrical coordinates for a multilayered system is based on Fourier's law of heat conduction with apparent thermal property values assumed.

    “The governing equation, which is based on Fourier's law of heat conduction with apparent thermal property values assumed, is written as:”

  • The authors state this as an assumption.

    A Dirac delta function for the laser pulses is assumed, valid considering the ultrashort pulse duration (<500 fs) compared to the interval between pulses (~12.5 ns).

    “Assuming a Dirac delta function for the laser pulses, which is a valid assumption considering the ultrashort pulse duration (&lt;500 fs) compared to the interval between pulses (~12.5 ns)”

  • The paper relies on this without support.

    The heating and sensing occur on the top surface of the sample.

    “both the heating and sensing occur on the top surface of the sample;”

  • The authors state this as an assumption.

    The DC component of the pump heating can be neglected in the mathematical model for simplicity.

    “The reason is that the DC component of the pump heating is neglected in the mathematical model here for simplicity (similar to the practice in Ref. 24).”

  • The paper relies on this without support.

    The lock-in amplifier rejects the DC component of the pump heating in TDTR experiments.

    “This simplification is justified because the DC component is rejected by the lock-in amplifier in TDTR experiments.”

  • The authors state this as an assumption.

    The superlattice sample can be treated as a homogeneous thin film with thickness h_film and an effective thermal conductivity.

    “The superlattice sample is treated as a homogeneous thin film with thickness h film and an effective thermal conductivity.”

  • The authors state this as an assumption.

    In variable spot size TDTR, the through-plane thermal conductivity Kz is the same for the two sets of measurements.

    “the validity of this approach relies on the assumption that Kz is the same for the two sets of the measurements.”

  • The authors state this as an assumption.

    For well-studied condensed materials, the bulk heat capacity can be used for thin films because nanostructures do not significantly change the heat capacity.

    “This is usually a reasonable assumption for most of the well-studied condensed materials (e.g., Al, Si, SiO2, etc.) since the nanostructures do not significantly change the heat capacity. 177”

  • The authors state this as an assumption.

    The thermal model used in variable spot size TDTR assumes cylindrical symmetry.

    “the thermal model assumes a cylindrical symmetry.”

  • The paper relies on this without support.

    The thermal conductivity of some semiconductor materials extracted from TDTR experiments was found to depend on the modulation frequency or the laser spot size.

    “The thermal conductivity of some semiconductor materials extracted from TDTR experiments was found to depend on the modulation frequency or the laser spot size”

  • The paper relies on this without support.

    Most analyses of TDTR data to-date are based on solutions of the diffusion equation with the assumption that all the thermal excitations are in equilibrium with each other and a temperature field is well defined.

    “Most analyses of TDTR data to-date are based on solutions of the diffusion equation with the assumption that all the thermal excitations are in equilibrium with each other and a temperature field is well defined.”
15 of 15

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • Nominal Co/Pt multilayer totals 20 nm, not 19 nm

    Minor

    The specified stack has a 1 nm Pt layer, six repetitions of 0.5 nm Co plus 1 nm Pt, and a 10 nm Pt layer. These thicknesses total 20 nm rather than the stated 19 nm.

    Reported 19 · recomputed 20

  • FDTR phase subtraction has the wrong sign

    Minor

    The stated pump phase is the instrumentation phase minus the reference phase, while the probe phase also includes the thermal phase. Subtracting probe from pump therefore gives the negative of the thermal phase, not the thermal phase as stated.

2 of 2

Cites

Flagged first, then by citations

Research works printed but not linked: 10

  1. 2010, Materials Science in Microelectronics I: The Relationships Between Thin Film Processing and Structure
  2. 2007, Nano/Microscale Heat Transfer
  3. 2004, Thermal Conductivity: Theory, Properties, and Applications
  4. A. J. Schmidt , Ph.D. thesis, Massachusetts Institute of Technology, 2008.
  5. 1991, Handbook of Optical Constants of Solids
  6. 1959, Conduction of Heat in Solids
  7. 2000, Thermal Quadrupoles: Solving the Heat Equation Through Integral Transforms
  8. 2000, The Fourier Transform and Its Applications
  9. 2014, Length-Scale Dependent Phonon Interactions, 137
  10. 2002, The Scientist and Engineer's Guide to Digital Signal Processing

Cited by

Sorted by citations

Authors
Jiang, P., Qian, X., & Yang, R.
Affiliations
University of Colorado Boulder (US)
ORCID
Venue
Journal of Applied Physics
Publisher
AIP Publishing
Published
2018-10-28
Volume
124
Issue
16
ISSN
  • 0021-8979 (ISSN-L)
  • 1089-7550
DOI
10.1063/1.5046944
OpenAlex
W2810725316
Semantic Scholar
3d77af78da23fa45a01e27b35ff5cf4562acadfb
Cited by
424
References
230
Citations by year
2026: 69 · 2025: 81 · 2024: 77 · 2023: 46 · 2022: 49 · 2021: 51 · 2020: 34 · 2019: 16 · 2018: 1
FWCI
9.21
Type
journal article
Language
en
Open access
Locations
  • Journal of Applied Physics (publishedVersion)
  • arXiv (Cornell University) (submittedVersion)
  • OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information) (submittedVersion)
  • arXiv (Cornell University)
Funders
  • National Science Foundation (0635579, 0846561, 1512776)
  • Defense Advanced Research Projects Agency (FA8650-15-1-7524, FA9550-08-1-0078, FA9550-11-1-0109, FA9550-11-C-0034)
  • Small Business Innovative Research and Small Business Technology Transfer (DE-AR DE-AR0000743)
Topics
  • Physical Sciences › Materials Science › Materials Chemistry › Thermal properties of materials
  • Physical Sciences › Engineering › Mechanics of Materials › Thermography and Photoacoustic Techniques
  • Physical Sciences › Engineering › Mechanical Engineering › Mechanical and Thermal Properties Analysis
Keywords
time-domain thermoreflectance, thin films, bulk materials, ultrafast laser heating, thermal conductivity, thermal diffusivity, phonon transport, electron transport, interfaces, energy storage and conversion

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-21.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-21.

Cited sources are checked by gpt-6-sol.

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

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